1. Field of the Invention
The present invention relates to a sensor device and an optical apparatus having the same. In particular, the present invention is preferable for optical apparatuses such as a digital camera, a video camera and a film camera that have a range finding sensor for receiving light from a field to measure a distance to an object existing in the field and a photometric sensor for receiving light from a field to measure luminance of the field and can perform range finding and photometry with high accuracy.
2. Related Background Art
Up to now, a range finder is well known which measures a distance to a subject in an optical apparatus such as a camera. For example, a range finder is well known which, passes light from a subject through two optical systems arranged at a fixed distance to form a part of subject images on separate two line sensors and measures a distance to the subject by finding a correlation between the two subject images from output signals from the two line sensors.
In addition, a photometer is also well known which measures luminance (brightness) of a subject in an optical apparatus such as a camera. For example, the photometer passes light from a field through an optical system to cause an area sensor to receive the light, measures field luminance according to an intensity of an output signal of the area sensor, and uses the field luminance for exposure control of the optical apparatus. Various photometers such as a camera have been proposed which are devised so as to segment a sensor used in measurement of field luminance into a plurality of sensors to detect a difference of luminance in a main subject to be photographed and its background and, if the difference of luminance is equal to or larger than a predetermined amount, causes a strobe to emit light judging that the main subject is in a back light state, thereby making an exposure state of the main subject adequate.
Independent separate sensors and optical systems are generally used as a line sensor and an optical system thereof used in the range finder and an area sensor and an optical system thereof used in the photometer. Therefore, if both the range finder and the photometer are mounted on a camera or the like, separate spaces for arranging each of them are required, which becomes a restriction on design of the camera or the like and, at the same time, leads to increase in a size of the camera or the like. In addition, when an interval between the range finder and the photometer is large, parallax of a range finding center and a photometric center occurs. Thus, for example, even if the range finding center catches a main subject depending on a distance to a subject, the photometric center catches the background, which may result in a case in which a photographed picture (image) is focused but has inadequate exposure.
In order to solve the above-mentioned problem, it has been proposed to integrate a range finder and a photometer in U.S. Pat. No. 5,302,997, Japanese Patent Application Laid-Open No. 09-329818 and the like. In these proposals, a pair of line sensors for range finding are arranged a fixed baseline length apart from each other, and an area sensor for photometry is arranged in a position between the pair of line sensors. Moreover, both the sensors are formed on one substrate (chip) and, at the same time, an optical system corresponding to each sensor is provided.
These proposals have an advantage in that, since it is sufficient to prepare only a space for the above-mentioned integrated device in a camera or the like, restriction on design is eliminated and, at the same time, since an interval between the range finder and the photometer is significantly reduced, the problem of parallax of the range finding center and the photometric center can be controlled to minimum.
U.S. Pat. No. 5,302,997 and Japanese Patent Application Laid-Open No. 09-329818 describe a structure as a sensor to some extent. However, there are no detailed descriptions concerning a structure as a device including an optical system and a case in which the device is incorporated in an optical apparatus such as a camera. Thus, there are following problems in materializing the inventions as products:
(i) If the range finder and the photometer are separately constituted, the sensors are also separate chips as shown in FIGS. 7A and 7B. A size of a chip 301 of range finding sensors 301a and 301b generally depends on a size of the range finding sensors. A size of a chip 302 for a photometric sensor 302c generally depends on a size of the photometric sensor. Thus, each sensor chip is efficient and is relatively excellent in terms of chip costs.
On the other hand, when the respective sensors are integrated into one chip as shown in FIG. 8, a size of a sensor chip 410 in a vertical direction in the figure depends on a dimension of a photometric sensor 401c. In addition, a size of the sensor chip 410 in a horizontal direction in the figure depends on a dimension of range finding sensors 401a and 401b and a dimension of a photometric sensor 401c. As is seen from FIG. 8, there are dead spaces above and below the range finding sensors 401a and 401b. Thus, the sensor chip is less efficient and has extremely high chip costs.
(ii) If the range finder and the photometer are separately constituted, as in a range finder of FIG. 9A and a photometer of FIG. 9B, light shielding walls 501 to 505 are arranged between optical systems 303a, 303b and 303c and sensors 301a, 301b and 302c generally in a vertical direction from sensor surfaces such that light other than light made incident from the optical systems corresponding to the sensors is not made incident on the sensors.
When the range finding sensors 301a and 301b and the photometric sensor 302c are integrated into one chip, it is expected that external light made incident from the photometric lens 303c is made incident on the range finding sensor 301a and 301b or external light made incident from the range finding lenses 303a and 303b is made incident on the photometric sensor 302c. In such cases, the incidence of external light adversely affects range finding accuracy and photometry accuracy, respectively. Thus, U.S. Pat. No. 5,302,997 it is described that it is sufficient to provide appropriate preventive walls in order to cope with this problem. If this is materialized, light shielding walls 601 to 604 are constituted in a vertical direction from sensor surfaces 401a, 401b and 401c as shown in FIG. 10.
However, the above-mentioned conventional example does not describe a size of each sensor, and sizes of optical systems, a focal length and the like corresponding to each sensor. When these are taken into account, the light shielding walls cannot be arranged in the vertical direction with respect to the sensor surfaces.
The present invention has been devised in view of the above-mentioned drawbacks and therefore, it is an object of the present invention to provide a sensor device and an optical apparatus having the same that are preferable for a digital camera, a video camera, a film camera and the like, in which a range finding sensor, a photometric sensor and the like can be easily formed on an identical substrate (chip) while realizing miniaturization of the entire apparatus and which can perform range finding and photometry with high accuracy.
A sensor device according to the present invention includes: a substrate having formed thereon first and second line sensors that are arranged a fixed baseline length apart from each other and a third sensor for receiving light from a field which is arranged on a line in an arrangement direction of the first and second line sensors; a first light receiving optical unit for condensing light from the field onto the first line sensor; a second light receiving optical unit for condensing light from the field onto the second line sensor; and a third light receiving optical unit for condensing light from the field onto the third sensor, wherein, when focal lengths of said first, second, and third light receiving optical units are assumed to be f1, f2, and f3, respectively, the following condition is satisfied: f1=f2xe2x89xa7f3.
Further characteristics of the present invention will be apparent from accompanying drawings and descriptions of the present invention.